Preclean and encapsultaion of microled features

ABSTRACT

Method for cleaning and encapsulating microLED features are disclosed. Some embodiments provide for a wet clean process and a dry clean process to remove contaminants from the microLED feature. Some embodiments provide for the encapsulation of a clean microLED feature. Some embodiments provide improved crystallinity of the microLED feature and the capping layer. Some embodiments provide improved EQE of microLED devices formed from the disclosed microLED features.

TECHNICAL FIELD

Embodiments of the disclosure generally relate to methods of cleaningand encapsulating substrate materials. In particular, embodiments ofdisclosure relate to methods of cleaning and encapsulating microLEDfeatures.

BACKGROUND

MicroLED displays have been identified as the next-generation displaytechnology to replace traditional thin-film transistor liquid crystaldisplays (TFT-LCD) and organic LED (OLED) displays. MicroLEDs have theability to use very low power while providing high performance (e.g.,produce infinite contrast and high color gamut with low response times).Further, microLEDs can enable very high resolutions, are not susceptibleto burn in, and have very simple process flows in manufacturing, therebyenabling a low cost of production while allowing device manufacturers toincorporate very thin displays in devices where thickness real estate iscrucial (as no backlight or polarizer is needed). For reference, amicroLED measures less than 100 μm which can be 1/100 the size of aconventional LED. As noted, microLEDs are self-emissive and don'trequire a backlight.

However, microLEDs suffer from poor conversion of electrical energy intolight, also referred to as energy conversion efficiency. At currentefficiency levels, microLED technology cannot deliver on a key promiseof providing better efficiency than OLED. Therefore, there aresignificant advances needed in this area in order to make microLEDdisplay technology viable to the mass market.

Three main factors that determine the external quantum efficiency (EQE)of a microLED: extraction efficiency, injection efficiency, andradiative efficiency. Extraction efficiency entails how produced photonsget partially reflected into the device, where they may be reabsorbedand converted into heat. Injection efficiency describes how wellelectron-hole pairs undergo recombination to produce photons. Injectionefficiency is formally defined as the proportion of electrons passingthrough the device that are injected into the active region. Radiativeefficiency involves the proportion of all electron-hole recombinationevents in the active region that are radiative and producing photons.

Improvements in extraction and injection efficiency can be made byimproving the GaN crystal quality in the device as well as optimizingthe epitaxial layer structure to maximize radiative recombination in theactive region. However, impurities and defects in the device can enhancenon-radiative recombination and lower the overall efficiency of microLED(specifically the radiative efficiency). Most of these defects can arisefrom etching processes or atmospheric oxidization.

Accordingly, there is a need for methods to remove surface impurities,oxidation, and defects. Further, there is also a need for a deviceprotecting encapsulation layer. These methods have the potential toenhance microLED EQE.

SUMMARY

One or more embodiments of the disclosure are directed to a method ofcleaning a microLED feature. The method comprises exposing a microLEDfeature having a layer of etch residue to a wet clean environment toremove at least a portion of the layer of etch residue. The microLEDfeature having a layer of etch residue is exposed to a dry cleanenvironment to remove a portion of the layer of etch residue. ThemicroLED feature is encapsulated with a capping layer.

Additional embodiments of the disclosure are directed to a method ofcleaning a microLED feature. The method comprises etching a layeredsubstrate to form a microLED feature. The microLED feature has a layerof etch residue thereon. The microLED feature is exposed to a wet cleanenvironment to form a wet-clean microLED feature. The wet cleanenvironment comprises HCI. The wet-clean microLED feature is exposed toa dry clean environment to form a clean microLED feature. The dry cleanenvironment comprises trimethyl aluminum. The microLED feature isencapsulated with a capping layer. The capping layer comprises aluminumnitride and is formed by atomic layer deposition.

Further embodiments of the disclosure are directed to a method ofcleaning a microLED feature. The method comprises etching a layeredsubstrate to form a microLED feature. The microLED feature has a layerof etch residue thereon which comprises carbon and/or oxidecontaminants. The microLED feature is exposed to a wet clean environmentto remove carbon contaminants and form a wet-clean microLED feature. Thewet clean environment comprises HCI. The wet-clean microLED feature isexposed to a dry clean environment to remove oxide contaminants and forma clean microLED feature. The dry clean environment comprises trimethylaluminum. The microLED feature is encapsulated with a capping layercomprising aluminum nitride and formed by atomic layer deposition. Thecapping layer and surface of the clean microLED feature are bothcrystalline with similar orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a flowchart of an exemplary processing method according to oneor more embodiment of the disclosure;

FIG. 2 is a cross-sectional view of an exemplary substrate undergoingprocessing according to one or more embodiment of the disclosure;

FIG. 3 is a cross-sectional view of a microLED feature according to oneor more embodiment of the disclosure; and

FIG. 4 is a schematic view of a cluster tool according to one or moreembodiment of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

As used in this specification and the appended claims, the term“substrate” refers to a surface, or portion of a surface, upon which aprocess acts. It will also be understood by those skilled in the artthat reference to a substrate can also refer to only a portion of thesubstrate, unless the context clearly indicates otherwise. Additionally,reference to depositing on a substrate can mean both a bare substrateand a substrate with one or more films or features deposited or formedthereon

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers.

Substrates may be exposed to a pretreatment process to polish, etch,reduce, oxidize, hydroxylate, anneal, UV cure, e-beam cure and/or bakethe substrate surface. In addition to film processing directly on thesurface of the substrate itself, in the present disclosure, any of thefilm processing steps disclosed may also be performed on an underlayerformed on the substrate as disclosed in more detail below, and the term“substrate surface” is intended to include such underlayer as thecontext indicates. Thus for example, where a film/layer or partialfilm/layer has been deposited onto a substrate surface, the exposedsurface of the newly deposited film/layer becomes the substrate surface.

One or more embodiment of the disclosure is directed to a method ofcleaning a microLED feature. Some embodiments of the disclosureadvantageously improve the EQE of a microLED device fabricated from themicroLED feature cleaned according to one or more embodiment of thedisclosure.

For the avoidance of doubt, within this disclosure, a microLED featureis not a complete microLED device. Stated differently, the methodsdisclosed herein provide a cleaned and encapsulated microLED featurewhich may be further processed into an operable microLED device.

Referring to FIGS. 1 and 2, an exemplary method 100 begins with optionaloperation 105 where a microLED feature 250 is formed by etching alayered substrate 200. The layered substrate comprises a substratematerial 210 with a substrate surface 215. In some embodiments, thesubstrate material 210 comprises sapphire.

In the embodiments shown, the layered substrate 200 further comprises afirst layer 220, a second layer 230, and a third layer 240 on thesubstrate surface 215. In some embodiments, the first layer 220 and thethird layer 240 are comprised of the same material.

In some embodiments, the first layer 220 and the third layer 240comprise or consist essentially of GaN. As used in this regard, amaterial which “consists essentially of” a stated material comprisesgreater than or equal to about 95%, greater than or equal to about 98%,greater than or equal to about 99%, or greater than or equal to about99.5% of the stated material on an atomic basis. Further, the disclosureof a material composition (e.g. GaN) should not be understood to implyany specific stoichiometry.

In some embodiments, the second layer comprises a quantum well. Thequantum well of some embodiments comprises a plurality of InGaN/GaNpairs. In some embodiments, the number of pairs is in a range of about 2to about 10 pairs, in a range of about 4 to about 10 pairs or in a rangeof about 5 to about 8 pairs.

Without being bound by theory, it is believed that the indiumconcentration of the quantum well affects the output wavelength from themicroLED device. In some embodiments, the indium concentration of thequantum well is in a range of about 2 atomic percent to about 35 atomicpercent or in a range of about 5 atomic percent to about 30 atomicpercent. In some embodiments, the indium concentration of the quantumwell is less than or equal to about 5 atomic percent, about 15 atomicpercent, about 20 atomic percent, or greater than or equal to about 30atomic percent.

With reference to FIG. 3, the etching operation 105 removes the firstlayer 220, the second layer 230 and the third layer 240 frompredetermined regions R of the layered substrate 200 to expose thesubstrate surface 215 in the predetermined regions R. The remainingstack of the first layer 220, the second layer 230, and the third layer240 is referred to as a microLED feature 250.

The microLED feature 250 has an average width W and a height H. Theratio of the height H divided by the average width W is the aspect ratioof the microLED feature 250. In some embodiments, the aspect ratio ofthe microLED feature 250 is in a range of about 1:1 to about 20:1, in arange of about 2:1 to about 10:1, or in a range of about 5:1 to about10:1. In some embodiments, the aspect ratio of the microLED feature 250is about 8:1.

While a single microLED feature is shown, a single substrate 200 maycontain multiple microLED features 250. In some embodiments, the spacingbetween adjacent microLED features 250 is greater than or equal to about200 nm, greater than or equal to about 500 nm, or greater than or equalto about 1 μm.

In some embodiments, as shown, the microLED feature 250 has a mesa shapewith slanted sidewalls. However, the disclosure is not limited in thisregard and embodiments in which the sidewalls of the microLED feature250 are arranged differently are also within the scope of thisdisclosure.

The etching performed at operation 105 may be performed by any suitablemeans to remove the first layer 220, the second layer 230 and the thirdlayer 240. In some embodiments, the layered substrate 200 is etched by areactive ion etch (RIE). In some embodiments, the layered substrate 200is dry etched by exposure to a Cl₂/BCl₃ gas mixture. In someembodiments, the layered substrate 200 is wet etched by exposure to aKOH solution. In some embodiments, the layered substrate 200 is etchedby the dry etch Cl₂/BCl₃ gas mixture and then the KOH solution. Withoutbeing bound by theory, it is believed that the etch process includingboth a Cl₂/BCl₃ gas mixture and a KOH solution reduces surface roughnessand removes defects from the exposed surface 255.

Referring again to FIG. 2, the etching performed at operation 105 leavesa layer of etch residue 260 on the exposed surface 255 of the microLEDfeature 250. In embodiments, when operation 105 is not performed, themicroLED feature 250 begins method 100 having a layer of etch residue260. In some embodiments, the layer of etch residue 260 is present oneach of the surface of the first layer 220, the second layer 230 and thethird layer 240.

As shown in FIG. 2, the layer of etch residue 260 may not be continuous.In some embodiments, as shown, the layer of etch residue 260 may nothave a uniform thickness. In some embodiments, the average thickness ofthe layer of etch residue is in a range of about 1 Å to about 50 Å, in arange of about 5 Å to about 50 Å, in a range of about 10 Å to about 40Å, or in a range of about 20 Å to about 30 Å.

In some embodiments, the layer of etch residue 260 may not have auniform composition. In some embodiments, the layer of etch residuecomprises carbon contaminants, oxide contaminants and/or halogencontaminants. In some embodiments, when one or more of the first layer,the second layer, or the third layer comprises GaN, the oxidecontaminants comprise GaO. In some embodiments, the halogen contaminantsmay comprise chlorine atoms or ions.

Referring again to FIG. 1, in some embodiments, when operation 105 isnot performed, the method begins at 110 by exposing a microLED feature250 to a wet clean environment. In some embodiments, operation 110 isperformed after operation 105. The exposure of the microLED feature 250to the wet clean environment may also be referred to as wet cleaning themicroLED feature 250.

In some embodiments, wet cleaning the microLED feature 250 may beperformed by submerging the substrate 200 in a wet clean solution. Insome embodiments, the wet clean solution wet cleaning the microLEDfeature 250 may be performed by exposing the substrate 200 to a vapor ofthe cleaning solution within a processing chamber.

The wet clean environment may be any suitable environment which removesa portion of the layer of etch residue 260. In some embodiments, the wetclean environment removes at least some carbon contaminants from themicroLED feature. In some embodiments, the wet clean environment removesat least some oxide contaminants from the microLED feature 250.

The wet clean environment comprises one or more of a strong acid, anamine or an alcohol. In some embodiments, the strong acid is selectedfrom hydrochloric acid (HCl) and nitric acid (HNO₃). In someembodiments, the amine is selected from ammonia, dimethylamine,triethylamine, hydrazine, and hydrazine derivatives. In someembodiments, the alcohol is selected from methanol, ethanol, andisopropanol.

In some embodiments, the wet clean environment comprises a solution ofone or more of a strong acid, an amine or an alcohol with a solvent. Insome embodiments, the solvent is selected from water, an alcohol, anorganic solvent, or combinations thereof.

In some embodiments, the exposure parameters of the wet clean operation110 may be controlled. In some embodiments, the period of exposure maybe controlled. For example, the period of exposure may be in a range ofabout 1 second to about 3600 seconds (1 hour), in a range of about 1second to about 900 seconds, in a range of about 1 second to about 300seconds, in a range of about 1 second to about 120 seconds, in a rangeof about 1 second to about 60 seconds, in a range of about 30 seconds toabout 3600 seconds, in a range of about 60 seconds to about 3600seconds, in a range of about 120 seconds to about 3600 seconds, in arange of about 300 seconds to about 3600 seconds, in a range of about900 seconds to about 3600 seconds, in a range of about 1800 seconds toabout 3600 seconds or in a range of about 300 seconds to about 900seconds. In some embodiments, the period of exposure is about 10minutes.

In some embodiments, the temperature of the substrate 200 or the wetclean environment may be controlled. For example, the temperature of thesubstrate may be maintained at a temperature in a range of about 20° C.to about 100° C. or processed at the ambient temperature withoutspecific control of the temperature of the substrate 200.

In some embodiments, the concentration of the wet clean environment maybe controlled. For example, the concentration of the wet cleanenvironment may be in a range of about 1 ppm to 100% concentration. Insome embodiments, the concentration is in a range of about 1 ppm toabout 0.1%, 1%, 5% or 10%. In some embodiments, the concentration of thewet clean environment is about 100%.

In some embodiments, the wet clean environment comprises isopropanol andthe substrate is soaked for 10 minutes at ambient temperature.

In some embodiments, after exposure to the wet clean environment, thesubstrate 200 may be rinsed to remove any residual component of the wetclean environment. In some embodiments, the substrate 200 is rinsed withone or more of water, an alcohol, or an organic solvent.

In some embodiments, after exposure to the wet clean environment, thesubstrate 200 may be dried to remove any residual volatile component ofthe wet clean environment. In some embodiments, the substrate 200 isdried with an inert gas. In some embodiments, the inert gas comprisesone or more of hydrogen gas (H₂), nitrogen gas (N₂), or argon (Ar).

In some embodiments, the substrate 200 may be heated to dry thesubstrate 200. In some embodiments, the substrate 200 may be maintainedunder vacuum to dry the substrate.

The method continues at 120 by exposing the microLED feature 250 to adry clean environment. In some embodiments, as shown, operation 110 isperformed before operation 120. However, the scope of the disclosure isnot limited in this regard. In some embodiments, operation 120 may beperformed before operation 110. In some embodiments, operation 120 isperformed after operation 105. The exposure of the microLED feature 250to the dry clean environment may also be referred to as dry cleaning themicroLED feature 250.

Without limiting the scope of the disclosure, in one or moreembodiments, operation 120 is performed within a processing chamber. Inthese embodiments, the microLED feature 250 is exposed dry cleanenvironment by flowing a vapor of the dry clean environment into theprocessing chamber by flowing a vapor of the dry clean environment intothe processing chamber.

The dry clean environment may be any suitable environment which removesa portion of the layer of etch residue 260. In some embodiments, the dryclean environment removes at least some carbon contaminants from themicroLED feature 250. In some embodiments, the dry clean environmentremoves at least some oxide contaminants from the microLED feature 250.

The dry clean environment comprises one or more of an alkyl metalcompound, a silane, hydrogen gas, nitrogen trifluoride (NF₃), a thiol, asubstituted cyclohexadiene, or a substituted dihydropyrazine. In someembodiments, the alkyl metal compound comprises one or more of trimethylaluminum (TMA), trimethyl indium, trimethyl gallium, triethyl aluminum,or diethyl zinc.

In some embodiments, the alkyl metal compound consists essentially oftrimethyl aluminum. As used in this regard, an environment which“consists essentially of” a stated material comprises greater than orequal to about 95%, greater than or equal to about 98%, greater than orequal to about 99%, or greater than or equal to about 99.5% of thestated material on an molar basis, excluding any inert or non-reactivespecies.

In some embodiments, the exposure parameters of the dry clean operation120 may be controlled. In some embodiments, the period of exposure maybe controlled. For example, in some embodiments, the period of exposureis in a range of about 0.1 second to about 10 minutes. The dry cleanoperation may also pulse components of the dry clean environment intothe processing chamber. In some embodiments, the pulse durations are ina range of about 0.1 second to about 30 seconds, in a range of about 0.1seconds to about 10 seconds, in a range of about 0.1 seconds to about 5seconds or in a range of about 0.1 s to about 1 second.

In some embodiments, the pressure of the processing chamber may becontrolled. For example, in some embodiments, the pressure may be in arange of about 1 mTorr to about 760 Torr.

In some embodiments, the temperature of the processing chamber or thesubstrate 200 may be controlled. For example, in some embodiments, thetemperature may be maintained in a range of about 25° C. to about 500°C., in a range of about 100° C. to about 400° C., or in a range of about200° C. to about 300° C.

In some embodiments, the flow rate of the dry clean environment into theprocessing chamber may be controlled. For example, the dry cleanenvironment may be flowed into the processing chamber at a flow rate ina range of about 1 sccm to about 1 slm.

In a specific embodiment, TMA is flowed into a processing chambermaintained at 250° C. for 0.2 seconds at 0.6 Torr, followed by a N₂purge for 20 seconds. The processing chamber is then pumped down. Theabove process is repeated. In some embodiments, the above process may berepeated 5 times.

Without being bound by theory, it is believed that by separating the dryclean environment into separate pulses or bursts, the processing chamberis better able to pump put any volatile reaction byproducts. In sodoing, exposure to the dry clean environment, surface reactivity and/orcleaning effect is maximized.

After operations 110 and 120, at 130 the microLED feature 250 isencapsulated with a capping layer 270. In some embodiments, the microLEDfeature 250 is not exposed to air immediately before encapsulating themicroLED feature 250. Stated differently, after exposing the microLEDfeature 250 to the wet clean environment and the dry clean environment,the microLED feature is not exposed to air before encapsulating themicroLED feature 250.

Without being bound by theory, it is believed that preventing exposureto air before encapsulating the microLED feature 250 prevents theformation of oxide contaminants on the surface of the microLED feature250. It is believed that the prevention of oxide contaminants is onefactor in the crystallinity of the capping layer 270 as furtherdescribed below.

In some embodiments, an exposed surface 255 of the microLED feature 250is substantially free of contaminants before encapsulating the microLEDfeature 250. As used in this regard, a surface which is “substantiallyfree of contaminants” has a concentration of each of carbon, oxygen andhalogen atoms within the top 10 Å of the material of less than or equalto about 1 atomic percent, less than or equal to about 0.5 atomicpercent or less than or equal to about 0.1 atomic percent.Alternatively, a surface which is “substantially free of contaminants”may be qualitatively determined based on the crystalline quality of alater deposited encapsulating layer.

In some embodiments, the exposed surface 255 of the microLED feature 250is crystalline before encapsulating the microLED feature 250. As used inthis regard, a surface which is crystalline has less than or equal toabout 5 percent, less than or equal to about 2 percent, less than orequal to about 1 percent, or less than or equal to about 0.5 percentamorphous on a unit area basis.

In some embodiments, the capping layer is substantially conformal to theexposed surface 255 of the microLED feature 250. As used in this regard,a capping layer which is substantially conformal has a thickness atevery point which is within ±20%, within ±10%, within ±5%, or within ±2%of the average thickness of the capping layer.

In some embodiments, the capping layer 270 is selectively deposited onthe exposed surface 255 of the microLED feature 250 over the substratesurface 215. As used herein, terms like “selectively deposit”, mean thata first amount or thickness is deposited on a first surface and a secondamount or thickness is deposited on a second surface. The second amountor thickness is less than the first amount or thickness, or, in someembodiments, no amount is deposited on the second surface. As used inthis regard, the term “over” does not imply a physical orientation ofone surface on top of another surface, rather a relationship of thethermodynamic or kinetic properties of the chemical reaction with onesurface relative to the other surface. In some embodiments, not shown,the capping layer 270 is formed on the substrate surface 215. In someembodiments, where the capping layer 270 is formed on the substratesurface 215, the capping layer 270 is later etched or otherwise removedfrom the substrate surface 215.

In some embodiments, the capping layer 270 is formed by exposing themicroLED feature 250 to a metal precursor and a reactant. In someembodiments, the capping layer 270 is formed by chemical vapordeposition (CVD). In some embodiments, the capping layer 270 is formedby atomic layer deposition.

In some embodiments, the capping layer comprises or consists essentiallyof aluminum nitride. In some embodiments, the capping layer 270 isformed by sequentially exposing the microLED feature 250 to trimethylaluminum and a plasma formed from ammonia.

In some embodiments, during the formation of the capping layer 270, thesubstrate material 210 and/or the microLED feature 250 is maintained ata temperature in a range of about 150° C. to about 300° C., in a rangeof about 200° C. to about 300° C., or in a range of about 225° C. toabout 275° C. In some embodiments, during the formation of the cappinglayer 270, the substrate material 210 and/or the microLED feature 250 ismaintained at a temperature of about 250° C.

In some embodiments, when the capping layer 270 comprises aluminumnitride, the capping layer is substantially crystalline with a <100>orientation. In some embodiments, the capping layer 270 has the sameorientation as the layers 220, 230, 240 of the microLED feature 250.

In some embodiments, the capping layer 270 is hermetic. In someembodiments, the capping layer 270 inhibits and/or prevents oxidation ofthe microLED feature. As used in this regard, a “hermetic” layerprevents oxidation of any underlayers by exposure to air or water.

The capping layer 270 may be exposed to oxidative test conditions totest the hermeticity of the capping layer 270. Oxidative test conditionsmay include plasma enhanced atomic layer deposition of silicon oxide (60Å using BDEAS and 50 W O₂/Ar plasma) on the capping layer surface,exposure to a low powered (e.g. 50 W) O₂/Ar plasma, or exposure to steamat an elevated temperature (e.g. 400° C.) for an extended period of time(e.g. 2 hours). Regardless of the test method, the depth of oxygen atomswithin the capping layer 270 or the microLED feature 250 provides anindication of the hermeticity of the capping layer 270, (i.e. shallowerdepths of oxidation indicate better or higher hermeticity).

With reference to FIG. 4, additional embodiments of the disclosure aredirected to a processing system 900 for executing the methods describedherein. FIG. 4 illustrates a system 900 that can be used to process asubstrate according to one or more embodiment of the disclosure. Thesystem 900 can be referred to as a cluster tool. The system 900 includesa central transfer station 910 with a robot 912 therein. The robot 912is illustrated as a single blade robot; however, those skilled in theart will recognize that other robot 912 configurations are within thescope of the disclosure. The robot 912 is configured to move one or moresubstrate between chambers connected to the central transfer station910.

At least one pre-clean/buffer chamber 920 is connected to the centraltransfer station 910. The pre-clean/buffer chamber 920 can include oneor more of a heater, a radical source or plasma source. Thepre-clean/buffer chamber 920 can be used as a holding area for anindividual semiconductor substrate or for a cassette of wafers forprocessing. The pre-clean/buffer chamber 920 can perform pre-cleaningprocesses or can pre-heat the substrate for processing or can simply bea staging area for the process sequence. In some embodiments, there aretwo pre-clean/buffer chambers 920 connected to the central transferstation 910.

In the embodiment shown in FIG. 4, the pre-clean chambers 920 can act aspass through chambers between the factory interface 905 and the centraltransfer station 910. The factory interface 905 can include one or morerobot 906 to move substrate from a cassette to the pre-clean/bufferchamber 920. The robot 912 can then move the substrate from thepre-clean/buffer chamber 920 to other chambers within the system 900.

A first processing chamber 930 can be connected to the central transferstation 910. The first processing chamber 930 can be configured as a wetcleaning chamber and may be in fluid communication with one or more gasor liquid sources to provide one or more flows to the first processingchamber 930 to perform the wet clean process. The substrate can be movedto and from the processing chamber 930 by the robot 912 passing throughisolation valve 914.

Processing chamber 940 can also be connected to the central transferstation 910. In some embodiments, processing chamber 940 comprises a drycleaning chamber and is fluid communication with one or more reactivegas sources to provide flows to the processing chamber 940 to performthe dry clean process. The substrate can be moved to and from theprocessing chamber 940 by robot 912 passing through isolation valve 914.

In some embodiments, processing chamber 960 is connected to the centraltransfer station 910 and is configured to act as a capping layerdeposition chamber. The processing chamber 960 can be configured toperform one or more different deposition processes.

In some embodiments, the dry clean process occurs in the same processingchamber as the capping layer deposition process. In embodiments of thissort, the processing chamber 940 and processing chamber 960 can beconfigured to perform the clean and encapsulation processes on twosubstrates at the same time.

In some embodiments, each of the processing chambers 930, 940, and 960are configured to perform different portions of the processing method.For example, processing chamber 930 may be configured to perform the wetclean process, processing chamber 940 may be configured to perform thedry clean process, and processing chamber 960 may be configured toperform a capping layer deposition process. The skilled artisan willrecognize that the number and arrangement of individual processingchambers on the tool can be varied and that the embodiment illustratedin FIG. 4 is merely representative of one possible configuration.

In some embodiments, the processing system 900 includes one or moremetrology stations. For example metrology stations can be located withinpre-clean/buffer chamber 920, within the central transfer station 910 orwithin any of the individual processing chambers 930, 940, 960. Themetrology station can be any position within the system 900 that allowsfor measurement of the substrate without exposing the substrate to anoxidizing environment.

At least one controller 950 is coupled to one or more of the centraltransfer station 910, the pre-clean/buffer chamber 920, and processingchambers 930, 940, or 960. In some embodiments, there is more than onecontroller 950 connected to the individual chambers or stations and aprimary control processor is coupled to each of the separate controllersto control the system 900. The controller 950 may be one of any form ofgeneral-purpose computer processor, microcontroller, microprocessor,etc., that can be used in an industrial setting for controlling variouschambers and sub-processors.

The at least one controller 950 can have a processor 952, a memory 954coupled to the processor 952, input/output devices 956 coupled to theprocessor 952, and support circuits 958 to communication between thedifferent electronic components. The memory 954 can include one or moreof transitory memory (e.g., random access memory) and non-transitorymemory (e.g., storage).

The memory 954, or computer-readable medium, of the processor may be oneor more of readily available memory such as random access memory (RAM),read-only memory (ROM), floppy disk, hard disk, or any other form ofdigital storage, local or remote. The memory 954 can retain aninstruction set that is operable by the processor 952 to controlparameters and components of the system 900. The support circuits 958are coupled to the processor 952 for supporting the processor in aconventional manner. Circuits may include, for example, cache, powersupplies, clock circuits, input/output circuitry, subsystems, and thelike.

Processes may generally be stored in the memory as a software routinethat, when executed by the processor, causes the process chamber toperform processes of the present disclosure. The software routine mayalso be stored and/or executed by a second processor (not shown) that isremotely located from the hardware being controlled by the processor.Some or all of the method of the present disclosure may also beperformed in hardware. As such, the process may be implemented insoftware and executed using a computer system, in hardware as, e.g., anapplication specific integrated circuit or other type of hardwareimplementation, or as a combination of software and hardware. Thesoftware routine, when executed by the processor, transforms the generalpurpose computer into a specific purpose computer (controller) thatcontrols the chamber operation such that the processes are performed.

In some embodiments, the controller 950 has one or more configurationsto execute individual processes or sub-processes to perform the method.The controller 950 can be connected to and configured to operateintermediate components to perform the functions of the methods. Forexample, the controller 950 can be connected to and configured tocontrol one or more of gas valves, actuators, motors, slit valves,vacuum control, etc.

The controller 950 of some embodiments has one or more configurationsselected from: a configuration to move a substrate on the robot betweenthe plurality of processing chambers and metrology station; aconfiguration to load and/or unload substrates from the system; aconfiguration to etch a layered substrate; a configuration to wet cleana microLED feature; a configuration to dry clean a microLED feature;and/or a configuration to encapsulate a microLED feature.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, those skilled in the art will understand thatthe embodiments described are merely illustrative of the principles andapplications of the present disclosure. It will be apparent to thoseskilled in the art that various modifications and variations can be madeto the method and apparatus of the present disclosure without departingfrom the spirit and scope of the disclosure. Thus, the presentdisclosure can include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of cleaning a microLED feature, the method comprising: exposing a microLED feature having a layer of etch residue to a wet clean environment to remove at least a portion of the layer of etch residue; exposing the microLED feature having a layer of etch residue to a dry clean environment to remove a portion of the layer of etch residue; and encapsulating the microLED feature with a capping layer.
 2. The method of claim 1, further comprising etching a layered substrate to form the microLED feature having the layer of etch residue.
 3. The method of claim 2, wherein the layered substrate is etched by a reactive ion etching (RIE) process.
 4. The method of claim 1, wherein the layer of etch residue has an average thickness in a range of about 20 Å to about 30 Å.
 5. The method of claim 1, wherein the layer of etch residue comprises carbon contaminants and oxide contaminants.
 6. The method of claim 1, wherein the wet clean environment comprises one or more of a strong acid, an amine or an alcohol.
 7. The method of claim 1, further comprising rinsing and drying the microLED feature after exposure to the wet clean environment.
 8. The method of claim 1, wherein the microLED feature is exposed to the wet clean environment before exposure to the dry clean environment.
 9. The method of claim 1, wherein the dry clean environment comprises an alkyl metal compound.
 10. The method of claim 9, wherein the alkyl metal compound comprises one or more of trimethyl aluminum, trimethyl indium, trimethyl gallium, triethyl aluminum or diethyl zinc.
 11. The method of claim 1, wherein the dry clean environment comprises one or more of a silane, hydrogen, nitrogen trifluoride, a thiol, a substituted cyclohexadiene, or a substituted dihydropyrazine.
 12. The method of claim 1, wherein the microLED feature is not exposed to air immediately before encapsulating the microLED feature.
 13. The method of claim 1, where in an exposed surface of the microLED feature is substantially free of contaminants and crystalline before encapsulating the microLED feature.
 14. The method of claim 1, wherein the capping layer consists essentially of aluminum nitride.
 15. The method of claim 14, wherein the capping layer is crystalline with a <100> orientation.
 16. The method of claim 1, wherein the capping layer is formed by atomic layer deposition.
 17. The method of claim 16, wherein the capping layer is formed by sequentially exposing the microLED feature to trimethyl aluminum and a plasma formed from ammonia.
 18. The method of claim 1, wherein the capping layer is hermetic and prevents oxidation of the microLED feature.
 19. A method of cleaning a microLED feature, the method comprising: etching a layered substrate to form a microLED feature, the microLED feature having a layer of etch residue thereon; exposing the microLED feature to a wet clean environment to form a wet-clean microLED feature, the wet clean environment comprising HCI; exposing the wet-clean microLED feature to a dry clean environment to form a clean microLED feature, the dry clean environment comprising trimethyl aluminum; and encapsulating the microLED feature with a capping layer, the capping layer comprising aluminum nitride and formed by atomic layer deposition.
 20. A method of cleaning a microLED feature, the method comprising: etching a layered substrate to form a microLED feature, the microLED feature having a layer of etch residue thereon, the layer of etch residue comprising carbon and/or oxide contaminants; exposing the microLED feature to a wet clean environment to remove carbon contaminants and form a wet-clean microLED feature, the wet clean environment comprising HCl; exposing the wet-clean microLED feature to a dry clean environment to remove oxide contaminants and form a clean microLED feature, the dry clean environment comprising trimethyl aluminum; and encapsulating the microLED feature with a capping layer, the capping layer comprising aluminum nitride and formed by atomic layer deposition, wherein the capping layer and surface of the clean microLED feature are both crystalline with similar orientation. 